Recently printing devices, such as an inkjet printer and an inkjet plotter, in which an inkjet recording method is adopted, are widely used in not only printers for general consumers but also industrial applications such as formation of an electronic circuit, fabrication of a color filter for a liquid crystal display, and fabrication of an organic EL display.
A liquid discharge head that discharges a liquid is mounted as a printing head in the inkjet printing device. Generally a thermal type and a piezoelectric type are well known in this kind of printing head. In the thermal type, a heater that is of pressurizing means is included in an ink channel filled with ink, the ink is heated and boiled by the heater to generate a bubble in the ink channel, the ink is pressurized by the bubble, and the ink is discharged as a liquid droplet through an ink discharge hole. In the piezoelectric type, a wall of the ink channel filled with the ink is partially flexed and displaced by a displacement element, the ink in the ink channel is mechanically pressurized, and the ink is discharged as the liquid droplet through the ink discharge hole.
A serial type and a line type are also well known in the liquid discharge head. In the serial type, recording is performed while the liquid discharge head is moved in a direction orthogonal to a recording medium conveying direction. In the line type, the recording is performed to the recording medium conveyed in a sub-scanning direction, while the liquid discharge head that is longer than the recording medium in a main scanning direction is fixed, or while a plurality of liquid discharge heads are arrayed such that a recording range becomes wider than the recording medium. In the line type, it is not necessary to move the liquid discharge head unlike the serial type. Therefore, the line type has an advantage that high-speed recording can be performed.
In both the serial type liquid discharge head and the line type liquid discharge head, it is necessary to increase density of the liquid discharge hole, which is formed in the liquid discharge head to discharge the liquid droplet, in order to perform high-density recording.
Therefore, there is well known a liquid discharge head that is configured to stack a manifold, a flow channel member, and an actuator unit (for example, see Patent Document 1). The flow channel member includes an individual flow channel that connects the manifold and the liquid discharge hole through a common flow channel, a throttle, a liquid pressurizing chamber, and a communication passage. The actuator unit includes a plurality of displacement elements each of which is provided such that the liquid pressurizing chamber is covered therewith. In the liquid discharge head of Patent Document 1, a corns-section area of the communication passage is kept constant. The liquid pressurizing chambers that are connected to the plurality of liquid discharge holes are disposed in a matrix array, and the displacement element is provided in the actuator unit such that the liquid pressurizing chamber is covered therewith. The displacement element is displaced to discharge the liquid droplet through the liquid discharge hole connected to each liquid pressurizing chamber, and printing can be performed with resolution of 600 dpi in the main scanning direction. The flow channel member is made by stacking a plurality of metallic plates. In the piezoelectric actuator, a piezoelectric ceramic layer, a common electrode, a piezoelectric ceramic layer, and an individual electrode are sequentially stacked from the flow channel member side.